Hyperspectral imaging is a form of spectral imaging wherein information from across the electromagnetic spectrum is collected in many narrow spectral bands and processed. From the different spectral images that are collected, information of the objects that are imaged can be derived. For example, as certain objects leave unique spectral signatures in images which may even depend on the status of the object, information obtained by multi-spectral imaging can provide information regarding the presence and/or status of objects in a region that is imaged. After selection of a spectral range that will be imaged, as spectral images in this complete spectral range can be acquired, one does not need to have detailed prior knowledge of the objects, and post-processing may allow to obtain all available information. Whereas originally hyperspectral remote sensing was mainly used for mining and geology, other applications such as ecology, agriculture and surveillance also make use of the imaging technique.
It is known to use photogrammetric techniques to infer three-dimensional information, in particular elevation information, from the acquired two-dimensional images. An example of such a technique is disclosed in Alsadik, B. S., Gerke, M., & Vosselman, G. (2012), “Optimal Camera Network Design For 3D Modeling Of Cultural Heritage”, ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, I-3, 7-12.
Some agricultural and ecological applications are known wherein hyperspectral remote sensing is used, e.g. for monitoring the development and health of crops, grape variety detection, monitoring individual forest canopies, detection of the chemical composition of plants as well as early detection of disease outbreaks, monitoring of impact of pollution and other environmental factors, etc. are some of the agricultural applications of interest. Hyperspectral imaging also is used for studies of inland and coastal waters for detecting biophysical properties. In mineralogy, detection of valuable minerals such as gold or diamonds can be performed using hyperspectral sensing, but also detection of oil and gas leakage from pipelines and natural wells are envisaged. Detection of soil composition on earth or even at other planets, asteroids or comets also are possible applications of hyperspectral imaging. In surveillance, hyperspectral imaging can for example be performed for detection of living creatures.
International patent application publication WO 2011/073430 A1, in the name of the present applicant, discloses a sensing device for obtaining geometric referenced multi-spectral image data of a region of interest in relative movement with respect to the sensing device. The sensing device comprises a first two dimensional sensor element and a spectral filter. The spectral filter and the first sensor element are arranged for obtaining spectral information at a first wavelength or wavelength range using a part of the first sensor element and for obtaining spectral information at a second wavelength or wavelength range using another part of the first sensor element. As a result of this arrangement, different parts of a single image acquired with the first sensor will represent the imaged scenery as seen is radiation of a different respective wavelength.
To date, there is no satisfactory way to apply the aforementioned photogrammetric techniques to multispectral images such as those acquired by means of the first sensor of WO 2011/073430 A1.